Enable Anonymous Access on an existing Web Application

SharePoint 2010 Central Administration/Application Management/Manage web applications

Click "SharePoint - 80"

Click "Authentication Providers"

Click "Default"

Select "Enable Anonymous Access"

Anonymouse Access Restrictions

SharePoint 2010 Central Administration

Grant permission to Anonymous users

Open http://k2/ website

Site Actions/Site Permissions

All configurations are through SharePoint interface. Don't try IIS manager for anonymous configuration.

The two things you must use IIS Manager are the IP address bindings and SSL certificate binding.